FOREWORD

Motor vehicle crashes on the Nation's roadways extract a high toll on American productivity and quality of life. Highway and traffic engineers have been in pursuit of relatively low-cost safety improvements that might have the potential to reduce crashes, save lives, reduce injuries, and lower property damage. For many rural areas, low-cost safety treatments are the only affordable option.

This report describes a driving simulator experiment designed to evaluate two sets of alternative low-cost safety improvements for rural areas. The first set of improvements is directed at enhancing the visibility of curves on rural two-lane undivided roads at night. The second set of improvements is directed at slowing traffic on rural two-lane undivided roads in small towns. This report should be of interest to highway engineers, traffic engineers, highway safety specialists, local planners, researchers, and others involved in the design and operation of rural roadways.

Raymond A. KrammesActing Director, Office of SafetyResearch and Development

Notice

This document is disseminated under the sponsorship of the
U.S. Department of Transportation in the interest of information exchange. The
U.S. Government assumes no liability for the use of the information contained in this document.

The
U.S. Government does not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

This experiment was sponsored by the Low Cost Safety Improvements Pooled Fund Study. It focused on two areas: (1) advanced detection and speed reduction for curves in rural two-lane roads at night and (2) traffic calming for small rural towns during the day. The experiment was conducted in the Federal Highway Administration's (FHWA) Highway Driving Simulator (HDS). Speed reduction in curves yielded the following order of tested treatments (from best to worst): (1) post-mounted delineators (PMDs) enhanced by streaming light-emitting diode (LED) lights slowed drivers down the most (9 mi/h (14.5 km/h)); (2) standard PMDs slowed drivers down by 7 to 8 mi/h (11.3 to 12.9 km/h); and (3) edge lines slowed drivers down by 2 mi/h (3.2 km/h). The same order was obtained for increases in the distance at which drivers were able to identify either the direction or the severity of the curve ahead as follows: streaming LED PMDs increased detection distance the most (560 to 1,065 ft (171 to 325 m)); standard PMDs increased detection distance by 45 to 200 ft (13.7 to 61 m); and edge lines increased detection distance by zero to 25 ft (zero to 7.6 m). PMDs performed better than pavement markings. The streaming PMDs solution offered the greatest potential increase in recognition distance. Speed reduction in towns yielded the following order of tested treatments: (1) chicanes slowed drivers down the most by 4 to 9 mi/h (6.4 to 14.5 km/h); (2) parked cars on both sides of the road slowed drivers 4 mi/h (6.4 km/h); and (3) bulb-outs resulted in only a small speed reduction of 1 mi/h (1.6 km/h) or none at all. In the case of towns, two low-cost safety solutions are worthy of further study: (1) adding painted chicanes to town entrances and (2) providing for and encouraging parking in the town. The results of this experiment do not take into account other hazardous factors that exist in the real world. Therefore, field validation is recommended for most of the above findings.